Carriage lock apparatus

ABSTRACT

A carriage on which a head is mounted has a rack which can be engaged with gear teeth located on a specific position. The gear teeth can be moved so as to engage with and disengage from the rack. The rack has a first pitch different from a second pitch of the gear teeth so as to maintain sure engagement.

This is a continuation, of application Ser. No. 07/437,971 filed Nov. 8,1989, now U.S. Pat. No. 5,008,876.

BACKGROUND OF THE INVENTION

The present invention relates to a carriage lock apparatus which isadvantageous in use in an optical disk apparatus, video disk player,compact disk player, and so on.

At the time of recording or playing back information on or from anoptical disk for instance, the optical disk is rotated and a head, fromwhich a laser beam is incident on the optical disk and through which areflected (or transmitted) beam from the optical disk is transmitted toa photo detector, is moved in a direction of the radius of optical disk.By this movement, information can be recorded or played back on or fromany track on the optical disk.

Accordingly, the head is needed to be kept in a movable state at thetime of use in a radial direction of the optical disk. During nonusetimes, however, if the head is movable, there is a possibility that itwill collide with stoppers etc. and be damaged when an apparatus isshocked or let to accidentally fall. Therefore, generally, a carriage onwhich the head is mounted and which is movable in the radial directionis locked in an unmovable state at the time of nonuse.

In a conventional apparatus, the carriage is locked on a chassis by ashipping screw or by an engagement of a projection and a hole or notchwhich are formed on one and another of the chassis and carriage.

However, it takes a relatively long time to lock the carriage by thescrew. Thus, such a system is advantageous when it is necessaryrepeatingly lock and unlock the carriage. Furthermore, it can not beused to lock automatically.

Also, the lock method of engagement between a projection and notchlimits a position for locking, namely the carriage is difficult to belocked in any radial position.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to eliminate thedisadvantages described above.

Another object of the invention is to provide a carriage lock apparatuswherein a carriage can be automatically locked in any radial position ina simple manner.

According to this invention, there is provided a carriage lock apparatuscomprising:

a head for recording playing back information on or a rotating disk;

a carriage on which the head is mounted;

first means for moving the carriage in a radial direction of the disk;

first engaging means, which has a first engaging portion with a firstpitch and which moves in association with a movement of the carriage inthe radial direction of disk;

second engaging means, which has a second engaging portion with a secondpitch different from the first pitch and which is located in a specificposition so that the second engaging portion can engage with the firstengaging portion; and

second means for engaging and disengaging either the first or secondengaging portions with and from another.

The carriage has the first engaging means the engaging portion of whichcan engage with the engaging portion of the second engaging means havingthe pitch different from that of the former. Accordingly, the carriagecan be locked automatically in any radial position in a stable andsimple manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an embodiment of a carriage lock apparatus inan optical disk system according to the present invention;

FIG. 2 is a front view of the embodiments of the carriage lock apparatusin an optical disk system of FIG. 1, wherein some parts have beenomitted for purposes of clarity;

FIG. 3 is a front view of the embodiment of the carriage lock apparatusin an optical disk system of FIG. 1;

FIG. 4 is a rear view of the embodiment of the carriage lock apparatusin an optical disk system of FIG. 1; and

FIGS. 5 and 6 are drawings explaining pitches of gear teeth according tothis invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 to 4 illustrate a structure of a preferred embodiment of acarriage lock apparatus according to the present invention.

In these figures, numeral 1 is a chassis on the right and left sides ofwhich two rods 2, each extending in a vertical direction in FIG. 1, arefixed. Numeral 3 is a carriage on which a head 4 is mounted. Head 4includes therein an actuator (not shown) which drives an objective lens(not shown) in a focusing direction perpendicular to the drawing in FIG.1 and a tracking direction vertical in FIG. 1. Numeral 5 designates ahole formed on head 4 through which a laser beam, radiated from opticalsource 21, and transmitted through the objective lens is incident on anoptical disk (not shown).

Numeral 6 (FIG. 3) designates a roller which is supported on carriage 3so as to rotate and comes in contact with rod 2 so that carriage 3 canmove along rod 2 in the radial direction of the optical disk (in avertical direction in FIG. 1). Numeral 7 is a yoke which is fixed onchassis 1 and is parallel to rod 2. On the inside of the yoke F is amagnet 8. Numeral 9 designates another yoke set on chassis 1 in parallelwith yoke 7. Yokes 7 and 9 are connected at both ends thereof by anotheryokes 11. Numeral 12 designates a space formed between magnet 8 and yoke9. Numeral 13 is a coil which is fixed on right and left sides ofcarriage 3 and in which yoke 9 is inserted.

Optical source 21, mounted on chassis 1, includes therein asemiconductor laser (not shown) which radiates a laser beam. Beamsplitter 22 mounted on chassis 1, deflects the laser beam emitted fromthe optical source 21 to a direction of the objective lens on head 4.The laser beam which is incident on the optical disk by the objectivelens and reflected by the optical disk returns in the same optical paththrough the objective lens. The reflected beam from the optical disk isreflected by beam splitter 22 and falls incident on a mirror such as ahalf mirror 23. The laser beam is divided into two beams, each of whichis incident to photo detectors 24 and 25, respectively. A tracking errorsignal and focusing signal are generated from outputs of the photodetectors 24 and 25, respectively. An RF signal according to theinformation recorded on the optical disk is derived from either the sumof the outputs of the photo detectors 24 and 25 or from just one ofthem.

Numeral 31 designates a plate which is fixed on the chassis 1 and twopins 32 are planted. Numeral 33 is a lock plate having a slot 34 inwhich the pins 32 are inserted. Numeral 35 is a slot which is formed onlock plate 33 and in which pin 36, fixed on lock lever 37, is inserted.Numeral 38 is a pin which is planted on chassis 1 and supports locklever 37 so that it can rotate on pin 38. Numeral 39 designates a clinchof lock lever 37 which is pushed by clinch 42 of cam plate 41. Numeral40 is a spring pulling lock lever 37 in a clockwise direction in FIG. 1.

Numeral 51 is a rack which has gear teeth 52 to 55 (at least two gearteeth 52 and 53) and can rotate on pin 56 planted on lock plate 33.Numeral 57 designates a stopper for limiting a rotation position of rack51. Numeral 61 designates a rack which is mounted on carriage 3 andwhich has an assembly of gear teeth 62.

The operation of the apparatus will now be described.

When a cartridge (not shown), in which the optical disk is enclosed, isloaded at a specific position in the optical disk apparatus, cam plate41 is moved by a means not shown in an upward direction in FIG. 1. Whencam plate 41 reaches a specific position, clinch 42 comes in contactwith clinch 39 of lock lever 37, which is pulled by spring 40 in aclockwise direction in FIG. 1. Because of the pushing of the clinch 39by clinch 42, lock lever 37 rotates on pin 38 in a counterclockwisedirection in FIG. 1, against the pulling force of the spring 40. Thus,pin 36 which is planted on lock lever 37 comes in contact with the leftside of slot 35 and lock plate 33, having slot 35, is pushed to theleft. Accordingly, lock plate 33 slides to the left and the movement isguided by the engagement between slot 34 formed on lock plate 33 and pin32 planted on plate 31 and inserted in slot 34. Gear teeth 52 to 55 onthe rack 51 supported on lock plate 33 through pin 56 results in themoving left and the engagement (lock) thereof with gear teeth 62 on rack61 is removed. When the loading of the cartridge is completed, cam plate41 is maintained in a position where clinch 39 is pressed by clinch 42so that carriage 3 is movable.

As a magnetic flux flows in a route of magnet 8, space 12, yoke 9, yoke11, yoke 7 and magnet 8, when an electric current flows in coil 13, anelectromagnetic force is generated on a portion of coil 13 positioned inspace 12 in a radial direction vertical in FIG. 1. As a result, carriage3 and head 4 mounted thereon are linearly moved in a radial directionalong rod 2, permitting information to be recorded and played back froma track on a specific radial position of the optical disk.

After the completion of the recording or playback operation and thecartridge is unloaded, cam plate 41 is moved down in FIG. 1 and locklever 37 rotates on pin 38 in a clockwise direction by the force ofspring 40. As pin 36, fixed on lock lever 37 results in the pressing ofthe right side of slot 35 formed on lock plate 33 in a right-warddirection, lock plate 33 is guided by pin 32 planted on plate 31 to moveright. Accordingly, at least one of the gear teeth 52 to 55 of rack 51engages with gear teeth 62 of rack 61, thereby locking carriage 3 sothat is cannot move.

Where gear teeth 62 of rack 61 and gear teeth 52 to 55 of rack 51 havethe same pitches to each other, the engagement thereof becomes difficultwhen these gear teeth are in such a position that the top of one geartooth confronts with that of the top of another tooth. Therefore, in thecarriage lock apparatus according to this invention, as shown in FIG. 5,when gear teeth 62 of rack 61 have a pitch P₀, gear teeth 52 and 53 havea pitch P different from P₀.

FIG. 6 shows the relationship of these pitches in detail. In order tomake the inside surface (right surface in FIG. 6) of gear tooth 52 (or53) come into contact with one gear tooth 62, the following formulashould be satisfied, where X₁ is the distance between the top of onegear tooth 52 and one gear tooth 62 and n is a positive integral number:

    2X.sub.1 =P-nP.sub.0                                       (1)

Similarly, where X₂ is a distance between the top of one gear tooth 52and one gear tooth 62, the condition to make the outside surface (leftsurface in FIG. 6) of gear tooth 52 (or 53) come into contact with onegear tooth 62 is as follows:

    2X.sub.2 =(n+1)P.sub.0 -P                                  (2)

When the following formula is satisfied, the engagement between thesegear teeth comes to be symmetrical, wherein

    X.sub.1 =X.sub.2                                           (3)

Therefore, the condition for symmetrical engagement is obtained bysolving the equation comprising the three formulas mentioned above, asfollows:

    P=nP.sub.0 +P.sub.0 /2                                     (4)

Formula (4) shows that when the pitch P in the gear teeth 52 and 53 havea phase difference against the gear teeth 62 by half the pitch P₀ ofgear teeth 62, the symmetrical engagement is achieved. In the carriagelock apparatus according to this invention, the pitches in gear teeth 52and 53 and 62 are set to satisfy the formula (4).

Therefore, when one of the tops of gear teeth 52 and 53 confronts with atop of one gear tooth 62, another of the tops of gear tooth 52 and 53confronts with a bottom of gear teeth 62. As a result, rack 51 slightlyrotates on pin 56 in a counterclockwise or clockwise direction at thetime of engagement between gear teeth and rack 61. Namely, the carriage3 moves a little in a vertical direction in FIG. 1 so as to absorb thedifference in the gear teeth phase. Accordingly, gear teeth 52 and 53engage with gear teeth 62.

Gear teeth 52 and 53 are located so that at least one of them engageswith gear teeth 62 even if carriage 3 is in an inside or outside limitposition within a radial movement range. Carriage 3 is thus able to belocked in any radial position.

Gear teeth 54 and 55 are added if necessary when it is difficult toobtain enough force to lock carriage 3 only by gear teeth 52 and 53. Thenumber of gear teeth is not limited to four.

In the embodiment described above, optical source 21 is located outsideof the head 4, but the former can be done inside of the latter.

Also, this invention can be applied to an apparatus wherein a head isrotated on a pivot in parallel with the disk as well as an apparatuswherein a head is moved linearly in a radial direction.

What is claimed is:
 1. A head lock apparatus, comprising:a head forrecording or playing back information on a rotating disk; means formoving said head in a radial direction on said rotating disk; firstengaging means, said first engaging means having a first engagingportion with a first pitch that moves in association with a movement ofsaid head in said radial direction of said rotating disk; secondengaging means, said second engaging means having a second engagingportion with a second pitch that is different from said first pitch ofsaid first engaging portion, said second engaging portion being locatedat a specific position so that said second engaging portion can engagesaid first engaging portion; and means for engaging or disengaging saidfirst and second engaging portions.
 2. A head lock apparatus accordingto claim 1, wherein said first engaging means is fixed to said head. 3.A head lock apparatus according to claim 1, wherein said means forengaging or disengaging comprises:a lock plate on which said secondengaging means is fixed; and a lock lever which rotates and moves saidlock plate so that said second engaging portion engages with andisengages from said first engaging portion.
 4. A head lock apparatusaccording to claim 3, wherein said engaging or disengaging means furthercomprises a cam plate which is moved in association with a loading ofsaid disk so as to rotate lock lever.
 5. A head lock apparatus accordingto claim 4, wherein said engaging or disengaging means further comprisesa spring for pulling said lock lever against a drive by said cam plate.6. A head lock apparatus according to claim 3, wherein said engaging ordisengaging means further comprises:a first slot formed in said lockplate; and a first pin planted on said lock lever and inserted in saidfirst slot.
 7. A head lock apparatus according to claim 6, wherein saidlock plate is mounted so as to slide by said lock lever, said engagingor disengaging means further comprising:a second slot formed in saidlock plate; and at least one second pin that is inserted in said secondslot so as to guide a sliding of said lock plate.
 8. A head lockapparatus according to claim 1, wherein one engaging portion comprisesat least two gear teeth and the other engaging portion comprises a rackwith gear teeth that are able to engage said at least two gear teeth. 9.A head lock apparatus according to claim 8, wherein said second engagingpotion comprises four gear teeth and said first engaging portioncomprises said rack with said gear teeth being able to engage said fourgear teeth of said second engaging portion.
 10. A head lock apparatusaccording to claim 8, wherein said gear teeth of said rack have a pitchP₀ as one of said first and second pitches, said at least two gear teethhaving a pitch P as another of said first and second pitches, X₁ being adistance between a top of one of said at least two gear teeth and a topof one of said gear teeth of said rack, and n being a positive integralnumber, so that the following formula is satisfied:

    2X.sub.1 =P-nP.sub.0.


11. A head lock apparatus according to claim 8, wherein said gear teethof said rack have a pitch P₀ as one of said first and second pitches,said at least two gear teeth having a pitch P as another of said firstand second pitches, X₂ being a distance between a top of one of said atleast two gear teeth and a top of one of said gear teeth of said rack,and n being a positive integral number, so that the following formula issatisfied:

    2X.sub.2 =(n+1)P.sub.0 -P2.


12. A head lock apparatus according to claim 8, wherein said gear teethof said rack have a pitch P₀ as one of said first and second pitches,said at least two gear teeth having a pitch P as another of said firstand second pitches, and n being a positive integral number, so that thefollowing formula is satisfied:

    P=nP.sub.0 +P.sub.0 /2.


13. A carriage lock apparatus, comprising:a carriage that is movable ina predetermined direction; first engaging means, said first engagingmeans having a first engaging portion with a first pitch that moves inassociation with a movement of said carriage in said predetermineddirection; second engaging means, said second engaging means having asecond engaging portion with a second pitch that is different from saidfirst pitch of said first engaging portion, said second engaging portionbeing located at a specific position so that said second engagingportion can engage first engaging portion; and means for engaging ordisengaging said first and second engaging portions.
 14. A carriage lockapparatus according to claim 13, wherein said first engaging means isfixed to said carriage.
 15. A carriage lock apparatus according to claim13, wherein said means for engaging or disengaging comprises:a lockplate on which said second engaging means is fixed; and a lock leverwhich rotates and moves said lock plate so that said second engagingportion engages with and disengages from said first engaging portion.16. A carriage lock apparatus according to claim 13, wherein saidcarriage that moves in a predetermined direction has a record/playbackhead that moves in a radical directing with respect to a rotating disk,so as to record information onto said rotating disk and to play backinformation recorded onto said rotating disk.
 17. A carriage lockapparatus according to claim 13, wherein one engaging portion comprisesat least two gear teeth and the other engaging portion comprises a rackwith gear teeth that are able to engage said at least two gear teeth.18. A carriage lock apparatus according to claim 17, wherein said secondengaging portion comprises four gear teeth and said first engagingportion comprises said rack with said gear teeth being able to engagefour gear teeth of said second engaging portion.
 19. A carriage lockapparatus, comprising:first engaging means having a first engagingportion with a first pitch that moves in association with a movement ofa carriage; second engaging means having a second engaging portion witha second pitch that is different from said first pitch of said firstengaging portion, said second engaging portion being located at apredetermined position so that said second engaging portion can engagesaid first engaging portion; and means for selectively engaging ordisengaging said first and second engaging portions so as to selectivelylock and unlock said carriage.
 20. The carriage lock apparatus of claim19, wherein one engaging portion comprises at least two engaging teeth,and another engaging portion comprises a rack having gear teeth that areable to engage said at least two engaging teeth, said gear teeth havinga pitch P₀, as one of said first and second pitches, said at least twoengaging teeth having a pitch P as another of said first and secondpitches, X₁ being a distance between a top of one of said at least twoengaging teeth and a top of one of said gear teeth of said rack, and nbeing a positive integral number, so that the following formula issatisfied:

    2X.sub.1 =P-nP.sub.0.


21. The carriage lock apparatus of claim 19, wherein one engagingportion comprises at least two engaging teeth, and another engagingportion comprises a rack having gear teeth that are able to engage saidat least two engaging teeth, said rack having a pitch P₀, as one of saidfirst and second pitches, said at least two engaging teeth having apitch P as another of said first and second pitches, X₂ being a distancebetween a top of one of said at least two engaging teeth and a top ofone of said gear teeth of said rack, and n being a positive integralnumber, so that the following formula is satisfied:

    2X.sub.2 =(n+1)P.sub.0 -P.


22. The carriage lock apparatus of claim 19, wherein one engagingportion comprises at least two engaging teeth, and another engagingportion comprises a rack having gear teeth that are able to engage saidat least two engaging teeth, said gear teeth of said rack having a pitchP₀, as one of said first and second pitches, said at least two engagingteeth having a pitch P as another of said first and second pitches, andn being a positive integral number, so that the following formula issatisfied:

    P=nP.sub.0 +P.sub.0 /2.